Various circuits are known for providing information from a digital source to an analog output such as a speaker. For example, common consumer applications such as portable music or communication devices provide digital data for conversion to an analog output such as a speaker or headphones. A goal for such devices is to reduce the amount of power used in driving its playback circuit such that there can be an increase in the playback time for the device. For certain audio playback devices, the audio quality relies on the dynamic range at negative 60 decibels power output. Various elements of the playback circuits, however, can create noise that necessitates consuming more power to overcome the noise introduced by those circuit elements.
FIG. 1 depicts one such known architecture for a circuit that provides an audio signal to a headphone for playback for a listener. In this architecture, an over-sampled sigma delta modulator 105 receives an audio signal from an UP-sampler circuit 110. The output of the over-sampled sigma delta modulator 105 is provided to a current steering digital to analog converter 115. The digital to analog converter 115 provides two outputs that are received by a current to voltage converter 120. The current to voltage converter includes multiple elements such as two resistors R1 and R2 and an amplifier A1. The output of this circuit is provided to a headphone amplifier 125. The headphone amplifier 125 includes multiple resistors R3, R4, R5, and R6 and a further amplifier. The output of the headphone amplifier 125 is provided to the headphone speakers that, in turn, produce the audible signal for the listener. In this circuit, the noise for the audio signal is created primarily by the current steering digital to analog converter 115, the current to voltage converter 120, and the headphone amplifier 125. The noise provided by the circuit elements results in a minimum power needed to drive the audio signal to have a sufficient audio quality above the background noise created by the circuit elements. Moreover, the noise created by the circuit elements negatively affects the dynamic range of the audio signal thereby reducing the audio quality experienced by the listener.